How Accurate Is Non-Invasive Blood Pressure Monitoring During Trendelenburg Laparoscopic Surgery?
For patients and families
In plain language
An automatic summary of structured registry data. It is an orientation aid, not a substitute for the official protocol or a physician assessment.
- What is being studied
- This is an observational study: the protocol does not assign a study treatment.
- Who it may be relevant to
- Registry conditions: Non-Invasive Blood Pressure Monitoring in Trendelenburg Position. Basic parameters: from 18 years · All.
- What needs checking
- Age, condition and sex are only basic indicators. Prior treatment, laboratory values and other mandatory requirements appear in the eligibility criteria below.
- Where it takes place
- Turkey (Türkiye)
- Next step
- Save the trial, show it to the treating physician, and confirm current recruitment with the study center. Costs, documents and travel →
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Official title
Accuracy of Non-Invasive Blood Pressure Monitoring During Laparoscopic Surgery in the Trendelenburg Position: A Prospective Error Grid Analysis
Overview
This study will test how accurate a blood pressure cuff is during certain types of surgery. During some abdominal surgeries done with small tools and a camera (called laparoscopic surgery), doctors place patients in a head-down position called the Trendelenburg position. In this position, it may be harder for the blood pressure cuff on the arm to give correct readings. This study will compare the cuff's readings (non-invasive) with readings from a thin tube placed inside an artery (invasive), which is more accurate but also more risky and uncomfortable. The researchers will use a method called error grid analysis to check how closely the cuff readings match the invasive ones. They hope to learn if the blood pressure cuff is accurate enough to be used safely in this kind of surgery. If it is, doctors may not need to use the invasive method as often. People 18 years or older who are already going to have invasive blood pressure monitoring as part of their planned surgery can join the study. The study will collect blood pressure measurements about every 20 minutes during surgery, as well as basic information like age, weight, and what medicines are given.
Detailed description
This is a prospective observational study designed to evaluate the clinical accuracy and reliability of non-invasive blood pressure (NIBP) monitoring in adult patients undergoing laparoscopic surgery in the Trendelenburg position. The accuracy of NIBP will be assessed by comparing it to invasive arterial blood pressure (IABP), which is considered the reference standard. The comparison will be performed using error grid analysis, a method that not only quantifies measurement differences but also categorizes the clinical risk of those discrepancies.
The Trendelenburg position, characterized by a head-down tilt of the patient, is frequently employed during gynecological and urological laparoscopic procedures to enhance surgical exposure. However, this positioning alters hemodynamic physiology and may influence peripheral blood pressure measurements. Previous evaluations of NIBP in this context have primarily relied on Bland-Altman analysis, which measures statistical agreement but does not assess the potential clinical consequences of disagreement between methods.
Error grid analysis overcomes this limitation by mapping paired NIBP and IABP values into predefined risk zones (A-E), based on their potential to affect clinical decision-making. Zone A reflects acceptable agreement with no risk of incorrect treatment, whereas Zones B through E indicate increasing levels of clinical risk.
In this study, NIBP and IABP will be measured simultaneously every 20 minutes throughout the procedure. The proportion of measurements falling within each error grid zone will be calculated. If fewer than 90% of the paired measurements fall within Zone A, NIBP will be considered insufficiently reliable for use in this surgical context without concurrent invasive monitoring.
A pilot study of five patients was conducted to estimate the intracluster correlation coefficient and design effect, which informed the final sample size calculation. Based on these preliminary data, a total of 100 patients is estimated to provide adequate statistical power to evaluate the primary outcome with 95% confidence and a 5% margin of error.
The study will also document intraoperative variables that may affect blood pressure measurement accuracy, including the use of vasoactive infusions. These data may provide insight into subgroups where NIBP reliability is particularly limited or acceptable.
The findings of this study may inform future monitoring protocols and could reduce unnecessary use of invasive lines in appropriately selected patients, improving patient safety and comfort while maintaining clinical accuracy.
Primary outcome measures
- Proportion of Paired Systolic Blood Pressure Measurements Within Zone A of the Error Grid [Time frame: Intraoperative period (measurements taken every 20 minutes during surgery)]
- Proportion of Paired Mean Arterial Pressure (MAP) Measurements Within Zone A of the Error Grid [Time frame: Intraoperative period (measurements taken every 20 minutes during surgery)]
Secondary outcome measures (4)
- Distribution of Paired Systolic Blood Pressure Measurements Across All Error Grid Zones (A-E) [Time frame: Intraoperative period (measurements taken every 20 minutes during surgery)]
- Distribution of Paired Mean Arterial Pressure (MAP) Measurements Across All Error Grid Zones (A-E) [Time frame: Intraoperative period (measurements taken every 20 minutes during surgery)]
- Effect of Antihypertensive Medication Use on the Accuracy of Systolic NIBP Measurements [Time frame: Intraoperative period (measurements taken every 20 minutes during surgery)]
- Effect of Antihypertensive Medication Use on the Accuracy of Mean Arterial Pressure (MAP) NIBP Measurements [Time frame: Intraoperative period (measurements taken every 20 minutes during surgery)]
Eligibility criteria
Inclusion criteria
- Age 18 years or older
- Scheduled to undergo laparoscopic surgery in the Trendelenburg position
- Will receive invasive arterial blood pressure monitoring as part of routine clinical care
Exclusion criteria
- Has peripheral artery disease
- Has congestive heart failure
Criteria are shown verbatim from the registry (in English). Final eligibility is always assessed by the study center.
Healthy volunteers: No
Study design
- Observational model
- Cohort
Study locations
Turkey (Türkiye) · 1 center
- Koc University Hospital — Istanbul
Publications
- Saugel B, Grothe O, Nicklas JY. Error Grid Analysis for Arterial Pressure Method Comparison Studies. Anesth Analg. 2018 Apr;126(4):1177-1185. doi: 10.1213/ANE.0000000000002585. PMID 29239945
Identifiers
NCT: NCT07107425 · 2025.243.IRB2.109